Biomaterials such as DNA are currently being explored as potential application in nanotechnology. DNA templates were immobilized on crystal-violet-treated mica by spin coating as a grid-like network. The DNA templates were then activated with PdCl2, followed by reduction with dimethylamine borane (DMAB) to form seeding nanoclusters on the DNA chain. Afterward the DNA chain with deposition of zero-valence Pd nanoclusters was grew in a Co electroless plating bath. SEM/EDS analysis revealed that Co nanoparticles could be assembled on the DNA template to form magnetic nanowires with a diameter of 25nm to 250nm by a conventional electroless plating. Vibrating Sample Magnetometer analysis indicated that Co-DNA nanowires showed a paramagnetic characteristic. Grid-like networks of DNA template were effectively preserved after Co electroless plating. These characteristics indicated that DNA is an ideal template for the production of magnetic nanowires, which could be useful in the development of high-density memory storage or magnetic field sensors.